/*
 * Copyright 2002-2015 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package cn.tang.tframe.common.utils.lang;

import cn.tang.tframe.common.utils.Assert;

import java.lang.reflect.Array;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

/**
 * Miscellaneous utility methods for number conversion and parsing.
 * Mainly for internal use within the framework; consider Apache's
 * Commons Lang for a more comprehensive suite of string utilities.
 *
 * @author Juergen Hoeller
 * @author Rob Harrop
 * @since 1.1.2
 */
public abstract class NumberUtils {

	private static final BigInteger LONG_MIN = BigInteger.valueOf(Long.MIN_VALUE);

	private static final BigInteger LONG_MAX = BigInteger.valueOf(Long.MAX_VALUE);

	/**
	 * Standard number types (all immutable):
	 * Byte, Short, Integer, Long, BigInteger, Float, Double, BigDecimal.
	 */
	public static final Set<Class<?>> STANDARD_NUMBER_TYPES;

	static {
		Set<Class<?>> numberTypes = new HashSet<Class<?>>(8);
		numberTypes.add(Byte.class);
		numberTypes.add(Short.class);
		numberTypes.add(Integer.class);
		numberTypes.add(Long.class);
		numberTypes.add(BigInteger.class);
		numberTypes.add(Float.class);
		numberTypes.add(Double.class);
		numberTypes.add(BigDecimal.class);
		STANDARD_NUMBER_TYPES = Collections.unmodifiableSet(numberTypes);
	}


	/**
	 * Convert the given number into an instance of the given target class.
	 * @param number the number to convert
	 * @param targetClass the target class to convert to
	 * @return the converted number
	 * @throws IllegalArgumentException if the target class is not supported
	 * (i.e. not a standard Number subclass as included in the JDK)
	 * @see Byte
	 * @see Short
	 * @see Integer
	 * @see Long
	 * @see BigInteger
	 * @see Float
	 * @see Double
	 * @see BigDecimal
	 */
	@SuppressWarnings("unchecked")
	public static <T extends Number> T convertNumberToTargetClass(Number number, Class<T> targetClass)
			throws IllegalArgumentException {

		Assert.notNull(number, "Number must not be null");
		Assert.notNull(targetClass, "Target class must not be null");

		if (targetClass.isInstance(number)) {
			return (T) number;
		}
		else if (targetClass.equals(Byte.class)) {
			long value = number.longValue();
			if (value < Byte.MIN_VALUE || value > Byte.MAX_VALUE) {
				raiseOverflowException(number, targetClass);
			}
			return (T) new Byte(number.byteValue());
		}
		else if (targetClass.equals(Short.class)) {
			long value = number.longValue();
			if (value < Short.MIN_VALUE || value > Short.MAX_VALUE) {
				raiseOverflowException(number, targetClass);
			}
			return (T) new Short(number.shortValue());
		}
		else if (targetClass.equals(Integer.class)) {
			long value = number.longValue();
			if (value < Integer.MIN_VALUE || value > Integer.MAX_VALUE) {
				raiseOverflowException(number, targetClass);
			}
			return (T) new Integer(number.intValue());
		}
		else if (targetClass.equals(Long.class)) {
			BigInteger bigInt = null;
			if (number instanceof BigInteger) {
				bigInt = (BigInteger) number;
			}
			else if (number instanceof BigDecimal) {
				bigInt = ((BigDecimal) number).toBigInteger();
			}
			// Effectively analogous to JDK 8's BigInteger.longValueExact()
			if (bigInt != null && (bigInt.compareTo(LONG_MIN) < 0 || bigInt.compareTo(LONG_MAX) > 0)) {
				raiseOverflowException(number, targetClass);
			}
			return (T) new Long(number.longValue());
		}
		else if (targetClass.equals(BigInteger.class)) {
			if (number instanceof BigDecimal) {
				// do not lose precision - use BigDecimal's own conversion
				return (T) ((BigDecimal) number).toBigInteger();
			}
			else {
				// original value is not a Big* number - use standard long conversion
				return (T) BigInteger.valueOf(number.longValue());
			}
		}
		else if (targetClass.equals(Float.class)) {
			return (T) new Float(number.floatValue());
		}
		else if (targetClass.equals(Double.class)) {
			return (T) new Double(number.doubleValue());
		}
		else if (targetClass.equals(BigDecimal.class)) {
			// always use BigDecimal(String) here to avoid unpredictability of BigDecimal(double)
			// (see BigDecimal javadoc for details)
			return (T) new BigDecimal(number.toString());
		}
		else {
			throw new IllegalArgumentException("Could not convert number [" + number + "] of type [" +
					number.getClass().getName() + "] to unknown target class [" + targetClass.getName() + "]");
		}
	}

	/**
	 * Raise an overflow exception for the given number and target class.
	 * @param number the number we tried to convert
	 * @param targetClass the target class we tried to convert to
	 */
	private static void raiseOverflowException(Number number, Class<?> targetClass) {
		throw new IllegalArgumentException("Could not convert number [" + number + "] of type [" +
				number.getClass().getName() + "] to target class [" + targetClass.getName() + "]: overflow");
	}

	/**
	 * Parse the given text into a number instance of the given target class,
	 * using the corresponding {@code decode} / {@code valueOf} methods.
	 * <p>Trims the input {@code String} before attempting to parse the number.
	 * Supports numbers in hex format (with leading "0x", "0X" or "#") as well.
	 * @param text the text to convert
	 * @param targetClass the target class to parse into
	 * @return the parsed number
	 * @throws IllegalArgumentException if the target class is not supported
	 * (i.e. not a standard Number subclass as included in the JDK)
	 * @see Byte#decode
	 * @see Short#decode
	 * @see Integer#decode
	 * @see Long#decode
	 * @see #decodeBigInteger(String)
	 * @see Float#valueOf
	 * @see Double#valueOf
	 * @see BigDecimal#BigDecimal(String)
	 */
	@SuppressWarnings("unchecked")
	public static <T extends Number> T parseNumber(String text, Class<T> targetClass) {
		Assert.notNull(text, "Text must not be null");
		Assert.notNull(targetClass, "Target class must not be null");
		String trimmed = StringUtils.trimAllWhitespace(text);

		if (targetClass.equals(Byte.class)) {
			return (T) (isHexNumber(trimmed) ? Byte.decode(trimmed) : Byte.valueOf(trimmed));
		}
		else if (targetClass.equals(Short.class)) {
			return (T) (isHexNumber(trimmed) ? Short.decode(trimmed) : Short.valueOf(trimmed));
		}
		else if (targetClass.equals(Integer.class)) {
			return (T) (isHexNumber(trimmed) ? Integer.decode(trimmed) : Integer.valueOf(trimmed));
		}
		else if (targetClass.equals(Long.class)) {
			return (T) (isHexNumber(trimmed) ? Long.decode(trimmed) : Long.valueOf(trimmed));
		}
		else if (targetClass.equals(BigInteger.class)) {
			return (T) (isHexNumber(trimmed) ? decodeBigInteger(trimmed) : new BigInteger(trimmed));
		}
		else if (targetClass.equals(Float.class)) {
			return (T) Float.valueOf(trimmed);
		}
		else if (targetClass.equals(Double.class)) {
			return (T) Double.valueOf(trimmed);
		}
		else if (targetClass.equals(BigDecimal.class) || targetClass.equals(Number.class)) {
			return (T) new BigDecimal(trimmed);
		}
		else {
			throw new IllegalArgumentException(
					"Cannot convert String [" + text + "] to target class [" + targetClass.getName() + "]");
		}
	}

	/**
	 * Parse the given text into a number instance of the given target class,
	 * using the given NumberFormat. Trims the input {@code String}
	 * before attempting to parse the number.
	 * @param text the text to convert
	 * @param targetClass the target class to parse into
	 * @param numberFormat the NumberFormat to use for parsing (if {@code null},
	 * this method falls back to {@code parseNumber(String, Class)})
	 * @return the parsed number
	 * @throws IllegalArgumentException if the target class is not supported
	 * (i.e. not a standard Number subclass as included in the JDK)
	 * @see NumberFormat#parse
	 * @see #convertNumberToTargetClass
	 * @see #parseNumber(String, Class)
	 */
	public static <T extends Number> T parseNumber(String text, Class<T> targetClass, NumberFormat numberFormat) {
		if (numberFormat != null) {
			Assert.notNull(text, "Text must not be null");
			Assert.notNull(targetClass, "Target class must not be null");
			DecimalFormat decimalFormat = null;
			boolean resetBigDecimal = false;
			if (numberFormat instanceof DecimalFormat) {
				decimalFormat = (DecimalFormat) numberFormat;
				if (BigDecimal.class.equals(targetClass) && !decimalFormat.isParseBigDecimal()) {
					decimalFormat.setParseBigDecimal(true);
					resetBigDecimal = true;
				}
			}
			try {
				Number number = numberFormat.parse(StringUtils.trimAllWhitespace(text));
				return convertNumberToTargetClass(number, targetClass);
			}
			catch (ParseException ex) {
				throw new IllegalArgumentException("Could not parse number: " + ex.getMessage());
			}
			finally {
				if (resetBigDecimal) {
					decimalFormat.setParseBigDecimal(false);
				}
			}
		}
		else {
			return parseNumber(text, targetClass);
		}
	}

	/**
	 * Determine whether the given value String indicates a hex number, i.e. needs to be
	 * passed into {@code Integer.decode} instead of {@code Integer.valueOf} (etc).
	 */
	private static boolean isHexNumber(String value) {
		int index = (value.startsWith("-") ? 1 : 0);
		return (value.startsWith("0x", index) || value.startsWith("0X", index) || value.startsWith("#", index));
	}

	/**
	 * Decode a {@link BigInteger} from a {@link String} value.
	 * Supports decimal, hex and octal notation.
	 * @see BigInteger#BigInteger(String, int)
	 */
	private static BigInteger decodeBigInteger(String value) {
		int radix = 10;
		int index = 0;
		boolean negative = false;

		// Handle minus sign, if present.
		if (value.startsWith("-")) {
			negative = true;
			index++;
		}

		// Handle radix specifier, if present.
		if (value.startsWith("0x", index) || value.startsWith("0X", index)) {
			index += 2;
			radix = 16;
		}
		else if (value.startsWith("#", index)) {
			index++;
			radix = 16;
		}
		else if (value.startsWith("0", index) && value.length() > 1 + index) {
			index++;
			radix = 8;
		}

		BigInteger result = new BigInteger(value.substring(index), radix);
		return (negative ? result.negate() : result);
	}

	/** Reusable Long constant for zero. */
	public static final Long LONG_ZERO = Long.valueOf(0L);
	/** Reusable Long constant for one. */
	public static final Long LONG_ONE = Long.valueOf(1L);
	/** Reusable Long constant for minus one. */
	public static final Long LONG_MINUS_ONE = Long.valueOf(-1L);
	/** Reusable Integer constant for zero. */
	public static final Integer INTEGER_ZERO = Integer.valueOf(0);
	/** Reusable Integer constant for one. */
	public static final Integer INTEGER_ONE = Integer.valueOf(1);
	/** Reusable Integer constant for minus one. */
	public static final Integer INTEGER_MINUS_ONE = Integer.valueOf(-1);
	/** Reusable Short constant for zero. */
	public static final Short SHORT_ZERO = Short.valueOf((short) 0);
	/** Reusable Short constant for one. */
	public static final Short SHORT_ONE = Short.valueOf((short) 1);
	/** Reusable Short constant for minus one. */
	public static final Short SHORT_MINUS_ONE = Short.valueOf((short) -1);
	/** Reusable Byte constant for zero. */
	public static final Byte BYTE_ZERO = Byte.valueOf((byte) 0);
	/** Reusable Byte constant for one. */
	public static final Byte BYTE_ONE = Byte.valueOf((byte) 1);
	/** Reusable Byte constant for minus one. */
	public static final Byte BYTE_MINUS_ONE = Byte.valueOf((byte) -1);
	/** Reusable Double constant for zero. */
	public static final Double DOUBLE_ZERO = Double.valueOf(0.0d);
	/** Reusable Double constant for one. */
	public static final Double DOUBLE_ONE = Double.valueOf(1.0d);
	/** Reusable Double constant for minus one. */
	public static final Double DOUBLE_MINUS_ONE = Double.valueOf(-1.0d);
	/** Reusable Float constant for zero. */
	public static final Float FLOAT_ZERO = Float.valueOf(0.0f);
	/** Reusable Float constant for one. */
	public static final Float FLOAT_ONE = Float.valueOf(1.0f);
	/** Reusable Float constant for minus one. */
	public static final Float FLOAT_MINUS_ONE = Float.valueOf(-1.0f);

	/**
	 * <p><code>NumberUtils</code> instances should NOT be constructed in standard programming.
	 * Instead, the class should be used as <code>NumberUtils.toInt("6");</code>.</p>
	 *
	 * <p>This constructor is public to permit tools that require a JavaBean instance
	 * to operate.</p>
	 */
	public NumberUtils() {
		super();
	}

	//-----------------------------------------------------------------------
	/**
	 * <p>Convert a <code>String</code> to an <code>int</code>, returning
	 * <code>zero</code> if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, <code>zero</code> is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toInt(null) = 0
	 *   NumberUtils.toInt("")   = 0
	 *   NumberUtils.toInt("1")  = 1
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @return the int represented by the string, or <code>zero</code> if
	 *  conversion fails
	 * @since 2.1
	 */
	public static int toInt(final String str) {
		return toInt(str, 0);
	}

	/**
	 * <p>Convert a <code>String</code> to an <code>int</code>, returning a
	 * default value if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, the default value is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toInt(null, 1) = 1
	 *   NumberUtils.toInt("", 1)   = 1
	 *   NumberUtils.toInt("1", 0)  = 1
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @param defaultValue  the default value
	 * @return the int represented by the string, or the default if conversion fails
	 * @since 2.1
	 */
	public static int toInt(final String str, final int defaultValue) {
		if(str == null) {
			return defaultValue;
		}
		try {
			return Integer.parseInt(str);
		} catch (final NumberFormatException nfe) {
			return defaultValue;
		}
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>long</code>, returning
	 * <code>zero</code> if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, <code>zero</code> is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toLong(null) = 0L
	 *   NumberUtils.toLong("")   = 0L
	 *   NumberUtils.toLong("1")  = 1L
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @return the long represented by the string, or <code>0</code> if
	 *  conversion fails
	 * @since 2.1
	 */
	public static long toLong(final String str) {
		return toLong(str, 0L);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>long</code>, returning a
	 * default value if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, the default value is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toLong(null, 1L) = 1L
	 *   NumberUtils.toLong("", 1L)   = 1L
	 *   NumberUtils.toLong("1", 0L)  = 1L
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @param defaultValue  the default value
	 * @return the long represented by the string, or the default if conversion fails
	 * @since 2.1
	 */
	public static long toLong(final String str, final long defaultValue) {
		if (str == null) {
			return defaultValue;
		}
		try {
			return Long.parseLong(str);
		} catch (final NumberFormatException nfe) {
			return defaultValue;
		}
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>float</code>, returning
	 * <code>0.0f</code> if the conversion fails.</p>
	 *
	 * <p>If the string <code>str</code> is <code>null</code>,
	 * <code>0.0f</code> is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toFloat(null)   = 0.0f
	 *   NumberUtils.toFloat("")     = 0.0f
	 *   NumberUtils.toFloat("1.5")  = 1.5f
	 * </pre>
	 *
	 * @param str the string to convert, may be <code>null</code>
	 * @return the float represented by the string, or <code>0.0f</code>
	 *  if conversion fails
	 * @since 2.1
	 */
	public static float toFloat(final String str) {
		return toFloat(str, 0.0f);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>float</code>, returning a
	 * default value if the conversion fails.</p>
	 *
	 * <p>If the string <code>str</code> is <code>null</code>, the default
	 * value is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toFloat(null, 1.1f)   = 1.0f
	 *   NumberUtils.toFloat("", 1.1f)     = 1.1f
	 *   NumberUtils.toFloat("1.5", 0.0f)  = 1.5f
	 * </pre>
	 *
	 * @param str the string to convert, may be <code>null</code>
	 * @param defaultValue the default value
	 * @return the float represented by the string, or defaultValue
	 *  if conversion fails
	 * @since 2.1
	 */
	public static float toFloat(final String str, final float defaultValue) {
		if (str == null) {
			return defaultValue;
		}
		try {
			return Float.parseFloat(str);
		} catch (final NumberFormatException nfe) {
			return defaultValue;
		}
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>double</code>, returning
	 * <code>0.0d</code> if the conversion fails.</p>
	 *
	 * <p>If the string <code>str</code> is <code>null</code>,
	 * <code>0.0d</code> is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toDouble(null)   = 0.0d
	 *   NumberUtils.toDouble("")     = 0.0d
	 *   NumberUtils.toDouble("1.5")  = 1.5d
	 * </pre>
	 *
	 * @param str the string to convert, may be <code>null</code>
	 * @return the double represented by the string, or <code>0.0d</code>
	 *  if conversion fails
	 * @since 2.1
	 */
	public static double toDouble(final String str) {
		return toDouble(str, 0.0d);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>double</code>, returning a
	 * default value if the conversion fails.</p>
	 *
	 * <p>If the string <code>str</code> is <code>null</code>, the default
	 * value is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toDouble(null, 1.1d)   = 1.1d
	 *   NumberUtils.toDouble("", 1.1d)     = 1.1d
	 *   NumberUtils.toDouble("1.5", 0.0d)  = 1.5d
	 * </pre>
	 *
	 * @param str the string to convert, may be <code>null</code>
	 * @param defaultValue the default value
	 * @return the double represented by the string, or defaultValue
	 *  if conversion fails
	 * @since 2.1
	 */
	public static double toDouble(final String str, final double defaultValue) {
		if (str == null) {
			return defaultValue;
		}
		try {
			return Double.parseDouble(str);
		} catch (final NumberFormatException nfe) {
			return defaultValue;
		}
	}

	//-----------------------------------------------------------------------
	/**
	 * <p>Convert a <code>String</code> to a <code>byte</code>, returning
	 * <code>zero</code> if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, <code>zero</code> is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toByte(null) = 0
	 *   NumberUtils.toByte("")   = 0
	 *   NumberUtils.toByte("1")  = 1
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @return the byte represented by the string, or <code>zero</code> if
	 *  conversion fails
	 * @since 2.5
	 */
	public static byte toByte(final String str) {
		return toByte(str, (byte) 0);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>byte</code>, returning a
	 * default value if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, the default value is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toByte(null, 1) = 1
	 *   NumberUtils.toByte("", 1)   = 1
	 *   NumberUtils.toByte("1", 0)  = 1
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @param defaultValue  the default value
	 * @return the byte represented by the string, or the default if conversion fails
	 * @since 2.5
	 */
	public static byte toByte(final String str, final byte defaultValue) {
		if(str == null) {
			return defaultValue;
		}
		try {
			return Byte.parseByte(str);
		} catch (final NumberFormatException nfe) {
			return defaultValue;
		}
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>short</code>, returning
	 * <code>zero</code> if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, <code>zero</code> is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toShort(null) = 0
	 *   NumberUtils.toShort("")   = 0
	 *   NumberUtils.toShort("1")  = 1
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @return the short represented by the string, or <code>zero</code> if
	 *  conversion fails
	 * @since 2.5
	 */
	public static short toShort(final String str) {
		return toShort(str, (short) 0);
	}

	/**
	 * <p>Convert a <code>String</code> to an <code>short</code>, returning a
	 * default value if the conversion fails.</p>
	 *
	 * <p>If the string is <code>null</code>, the default value is returned.</p>
	 *
	 * <pre>
	 *   NumberUtils.toShort(null, 1) = 1
	 *   NumberUtils.toShort("", 1)   = 1
	 *   NumberUtils.toShort("1", 0)  = 1
	 * </pre>
	 *
	 * @param str  the string to convert, may be null
	 * @param defaultValue  the default value
	 * @return the short represented by the string, or the default if conversion fails
	 * @since 2.5
	 */
	public static short toShort(final String str, final short defaultValue) {
		if(str == null) {
			return defaultValue;
		}
		try {
			return Short.parseShort(str);
		} catch (final NumberFormatException nfe) {
			return defaultValue;
		}
	}

	//-----------------------------------------------------------------------
	// must handle Long, Float, Integer, Float, Short,
	//                  BigDecimal, BigInteger and Byte
	// useful methods:
	// Byte.decode(String)
	// Byte.valueOf(String,int radix)
	// Byte.valueOf(String)
	// Double.valueOf(String)
	// Float.valueOf(String)
	// Float.valueOf(String)
	// Integer.valueOf(String,int radix)
	// Integer.valueOf(String)
	// Integer.decode(String)
	// Integer.getInteger(String)
	// Integer.getInteger(String,int val)
	// Integer.getInteger(String,Integer val)
	// Integer.valueOf(String)
	// Double.valueOf(String)
	// new Byte(String)
	// Long.valueOf(String)
	// Long.getLong(String)
	// Long.getLong(String,int)
	// Long.getLong(String,Integer)
	// Long.valueOf(String,int)
	// Long.valueOf(String)
	// Short.valueOf(String)
	// Short.decode(String)
	// Short.valueOf(String,int)
	// Short.valueOf(String)
	// new BigDecimal(String)
	// new BigInteger(String)
	// new BigInteger(String,int radix)
	// Possible inputs:
	// 45 45.5 45E7 4.5E7 Hex Oct Binary xxxF xxxD xxxf xxxd
	// plus minus everything. Prolly more. A lot are not separable.

	/**
	 * <p>Turns a string value into a java.lang.Number.</p>
	 *
	 * <p>If the string starts with {@code 0x} or {@code -0x} (lower or upper case) or {@code #} or {@code -#}, it
	 * will be interpreted as a hexadecimal Integer - or Long, if the number of digits after the
	 * prefix is more than 8 - or BigInteger if there are more than 16 digits.
	 * </p>
	 * <p>Then, the value is examined for a type qualifier on the end, i.e. one of
	 * <code>'f','F','d','D','l','L'</code>.  If it is found, it starts
	 * trying to create successively larger types from the type specified
	 * until one is found that can represent the value.</p>
	 *
	 * <p>If a type specifier is not found, it will check for a decimal point
	 * and then try successively larger types from <code>Integer</code> to
	 * <code>BigInteger</code> and from <code>Float</code> to
	 * <code>BigDecimal</code>.</p>
	 *
	 * <p>
	 * Integral values with a leading {@code 0} will be interpreted as octal; the returned number will
	 * be Integer, Long or BigDecimal as appropriate.
	 * </p>
	 *
	 * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
	 *
	 * <p>This method does not trim the input string, i.e., strings with leading
	 * or trailing spaces will generate NumberFormatExceptions.</p>
	 *
	 * @param str  String containing a number, may be null
	 * @return Number created from the string (or null if the input is null)
	 * @throws NumberFormatException if the value cannot be converted
	 */
	public static Number createNumber(final String str) throws NumberFormatException {
		if (str == null) {
			return null;
		}
		if (StringUtils.isBlank(str)) {
			throw new NumberFormatException("A blank string is not a valid number");
		}
		// Need to deal with all possible hex prefixes here
		final String[] hex_prefixes = {"0x", "0X", "-0x", "-0X", "#", "-#"};
		int pfxLen = 0;
		for(final String pfx : hex_prefixes) {
			if (str.startsWith(pfx)) {
				pfxLen += pfx.length();
				break;
			}
		}
		if (pfxLen > 0) { // we have a hex number
			char firstSigDigit = 0; // strip leading zeroes
			for(int i = pfxLen; i < str.length(); i++) {
				firstSigDigit = str.charAt(i);
				if (firstSigDigit == '0') { // count leading zeroes
					pfxLen++;
				} else {
					break;
				}
			}
			final int hexDigits = str.length() - pfxLen;
			if (hexDigits > 16 || (hexDigits == 16 && firstSigDigit > '7')) { // too many for Long
				return createBigInteger(str);
			}
			if (hexDigits > 8 || (hexDigits == 8 && firstSigDigit > '7')) { // too many for an int
				return createLong(str);
			}
			return createInteger(str);
		}
		final char lastChar = str.charAt(str.length() - 1);
		String mant;
		String dec;
		String exp;
		final int decPos = str.indexOf('.');
		final int expPos = str.indexOf('e') + str.indexOf('E') + 1; // assumes both not present
		// if both e and E are present, this is caught by the checks on expPos (which prevent IOOBE)
		// and the parsing which will detect if e or E appear in a number due to using the wrong offset

		int numDecimals = 0; // Check required precision (LANG-693)
		if (decPos > -1) { // there is a decimal point

			if (expPos > -1) { // there is an exponent
				if (expPos < decPos || expPos > str.length()) { // prevents double exponent causing IOOBE
					throw new NumberFormatException(str + " is not a valid number.");
				}
				dec = str.substring(decPos + 1, expPos);
			} else {
				dec = str.substring(decPos + 1);
			}
			mant = str.substring(0, decPos);
			numDecimals = dec.length(); // gets number of digits past the decimal to ensure no loss of precision for floating point numbers.
		} else {
			if (expPos > -1) {
				if (expPos > str.length()) { // prevents double exponent causing IOOBE
					throw new NumberFormatException(str + " is not a valid number.");
				}
				mant = str.substring(0, expPos);
			} else {
				mant = str;
			}
			dec = null;
		}
		if (!Character.isDigit(lastChar) && lastChar != '.') {
			if (expPos > -1 && expPos < str.length() - 1) {
				exp = str.substring(expPos + 1, str.length() - 1);
			} else {
				exp = null;
			}
			//Requesting a specific type..
			final String numeric = str.substring(0, str.length() - 1);
			final boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
			switch (lastChar) {
				case 'l' :
				case 'L' :
					if (dec == null
							&& exp == null
							&& (numeric.charAt(0) == '-' && isDigits(numeric.substring(1)) || isDigits(numeric))) {
						try {
							return createLong(numeric);
						} catch (final NumberFormatException nfe) { // NOPMD
							// Too big for a long
						}
						return createBigInteger(numeric);

					}
					throw new NumberFormatException(str + " is not a valid number.");
				case 'f' :
				case 'F' :
					try {
						final Float f = NumberUtils.createFloat(numeric);
						if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
							//If it's too big for a float or the float value = 0 and the string
							//has non-zeros in it, then float does not have the precision we want
							return f;
						}

					} catch (final NumberFormatException nfe) { // NOPMD
						// ignore the bad number
					}
					//$FALL-THROUGH$
				case 'd' :
				case 'D' :
					try {
						final Double d = NumberUtils.createDouble(numeric);
						if (!(d.isInfinite() || (d.floatValue() == 0.0D && !allZeros))) {
							return d;
						}
					} catch (final NumberFormatException nfe) { // NOPMD
						// ignore the bad number
					}
					try {
						return createBigDecimal(numeric);
					} catch (final NumberFormatException e) { // NOPMD
						// ignore the bad number
					}
					//$FALL-THROUGH$
				default :
					throw new NumberFormatException(str + " is not a valid number.");

			}
		}
		//User doesn't have a preference on the return type, so let's start
		//small and go from there...
		if (expPos > -1 && expPos < str.length() - 1) {
			exp = str.substring(expPos + 1, str.length());
		} else {
			exp = null;
		}
		if (dec == null && exp == null) { // no decimal point and no exponent
			//Must be an Integer, Long, Biginteger
			try {
				return createInteger(str);
			} catch (final NumberFormatException nfe) { // NOPMD
				// ignore the bad number
			}
			try {
				return createLong(str);
			} catch (final NumberFormatException nfe) { // NOPMD
				// ignore the bad number
			}
			return createBigInteger(str);
		}

		//Must be a Float, Double, BigDecimal
		final boolean allZeros = isAllZeros(mant) && isAllZeros(exp);
		try {
			if(numDecimals <= 7){// If number has 7 or fewer digits past the decimal point then make it a float
				final Float f = createFloat(str);
				if (!(f.isInfinite() || (f.floatValue() == 0.0F && !allZeros))) {
					return f;
				}
			}
		} catch (final NumberFormatException nfe) { // NOPMD
			// ignore the bad number
		}
		try {
			if(numDecimals <= 16){// If number has between 8 and 16 digits past the decimal point then make it a double
				final Double d = createDouble(str);
				if (!(d.isInfinite() || (d.doubleValue() == 0.0D && !allZeros))) {
					return d;
				}
			}
		} catch (final NumberFormatException nfe) { // NOPMD
			// ignore the bad number
		}

		return createBigDecimal(str);
	}

	/**
	 * <p>Utility method for {@link #createNumber(java.lang.String)}.</p>
	 *
	 * <p>Returns <code>true</code> if s is <code>null</code>.</p>
	 *
	 * @param str  the String to check
	 * @return if it is all zeros or <code>null</code>
	 */
	private static boolean isAllZeros(final String str) {
		if (str == null) {
			return true;
		}
		for (int i = str.length() - 1; i >= 0; i--) {
			if (str.charAt(i) != '0') {
				return false;
			}
		}
		return str.length() > 0;
	}

	//-----------------------------------------------------------------------
	/**
	 * <p>Convert a <code>String</code> to a <code>Float</code>.</p>
	 *
	 * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
	 *
	 * @param str  a <code>String</code> to convert, may be null
	 * @return converted <code>Float</code> (or null if the input is null)
	 * @throws NumberFormatException if the value cannot be converted
	 */
	public static Float createFloat(final String str) {
		if (str == null) {
			return null;
		}
		return Float.valueOf(str);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>Double</code>.</p>
	 *
	 * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
	 *
	 * @param str  a <code>String</code> to convert, may be null
	 * @return converted <code>Double</code> (or null if the input is null)
	 * @throws NumberFormatException if the value cannot be converted
	 */
	public static Double createDouble(final String str) {
		if (str == null) {
			return null;
		}
		return Double.valueOf(str);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>Integer</code>, handling
	 * hex and octal notations.</p>
	 *
	 * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
	 *
	 * @param str  a <code>String</code> to convert, may be null
	 * @return converted <code>Integer</code> (or null if the input is null)
	 * @throws NumberFormatException if the value cannot be converted
	 */
	public static Integer createInteger(final String str) {
		if (str == null) {
			return null;
		}
		// decode() handles 0xAABD and 0777 (hex and octal) as well.
		return Integer.decode(str);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>Long</code>;
	 * since 3.1 it handles hex and octal notations.</p>
	 *
	 * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
	 *
	 * @param str  a <code>String</code> to convert, may be null
	 * @return converted <code>Long</code> (or null if the input is null)
	 * @throws NumberFormatException if the value cannot be converted
	 */
	public static Long createLong(final String str) {
		if (str == null) {
			return null;
		}
		return Long.decode(str);
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>BigInteger</code>;
	 * since 3.2 it handles hex (0x or #) and octal (0) notations.</p>
	 *
	 * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
	 *
	 * @param str  a <code>String</code> to convert, may be null
	 * @return converted <code>BigInteger</code> (or null if the input is null)
	 * @throws NumberFormatException if the value cannot be converted
	 */
	public static BigInteger createBigInteger(final String str) {
		if (str == null) {
			return null;
		}
		int pos = 0; // offset within string
		int radix = 10;
		boolean negate = false; // need to negate later?
		if (str.startsWith("-")) {
			negate = true;
			pos = 1;
		}
		if (str.startsWith("0x", pos) || str.startsWith("0x", pos)) { // hex
			radix = 16;
			pos += 2;
		} else if (str.startsWith("#", pos)) { // alternative hex (allowed by Long/Integer)
			radix = 16;
			pos ++;
		} else if (str.startsWith("0", pos) && str.length() > pos + 1) { // octal; so long as there are additional digits
			radix = 8;
			pos ++;
		} // default is to treat as decimal

		final BigInteger value = new BigInteger(str.substring(pos), radix);
		return negate ? value.negate() : value;
	}

	/**
	 * <p>Convert a <code>String</code> to a <code>BigDecimal</code>.</p>
	 *
	 * <p>Returns <code>null</code> if the string is <code>null</code>.</p>
	 *
	 * @param str  a <code>String</code> to convert, may be null
	 * @return converted <code>BigDecimal</code> (or null if the input is null)
	 * @throws NumberFormatException if the value cannot be converted
	 */
	public static BigDecimal createBigDecimal(final String str) {
		if (str == null) {
			return null;
		}
		// handle JDK1.3.1 bug where "" throws IndexOutOfBoundsException
		if (StringUtils.isBlank(str)) {
			throw new NumberFormatException("A blank string is not a valid number");
		}
		if (str.trim().startsWith("--")) {
			// this is protection for poorness in java.lang.BigDecimal.
			// it accepts this as a legal value, but it does not appear
			// to be in specification of class. OS X Java parses it to
			// a wrong value.
			throw new NumberFormatException(str + " is not a valid number.");
		}
		return new BigDecimal(str);
	}

	// Min in array
	//--------------------------------------------------------------------
	/**
	 * <p>Returns the minimum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static long min(final long[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns min
		long min = array[0];
		for (int i = 1; i < array.length; i++) {
			if (array[i] < min) {
				min = array[i];
			}
		}

		return min;
	}

	/**
	 * <p>Returns the minimum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static int min(final int[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns min
		int min = array[0];
		for (int j = 1; j < array.length; j++) {
			if (array[j] < min) {
				min = array[j];
			}
		}

		return min;
	}

	/**
	 * <p>Returns the minimum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static short min(final short[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns min
		short min = array[0];
		for (int i = 1; i < array.length; i++) {
			if (array[i] < min) {
				min = array[i];
			}
		}

		return min;
	}

	/**
	 * <p>Returns the minimum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static byte min(final byte[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns min
		byte min = array[0];
		for (int i = 1; i < array.length; i++) {
			if (array[i] < min) {
				min = array[i];
			}
		}

		return min;
	}

	/**
	 * <p>Returns the minimum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 * @see IEEE754rUtils#min(double[]) IEEE754rUtils for a version of this method that handles NaN differently
	 */
	public static double min(final double[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns min
		double min = array[0];
		for (int i = 1; i < array.length; i++) {
			if (Double.isNaN(array[i])) {
				return Double.NaN;
			}
			if (array[i] < min) {
				min = array[i];
			}
		}

		return min;
	}

	/**
	 * <p>Returns the minimum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 * @see IEEE754rUtils#min(float[]) IEEE754rUtils for a version of this method that handles NaN differently
	 */
	public static float min(final float[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns min
		float min = array[0];
		for (int i = 1; i < array.length; i++) {
			if (Float.isNaN(array[i])) {
				return Float.NaN;
			}
			if (array[i] < min) {
				min = array[i];
			}
		}

		return min;
	}

	// Max in array
	//--------------------------------------------------------------------
	/**
	 * <p>Returns the maximum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static long max(final long[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns max
		long max = array[0];
		for (int j = 1; j < array.length; j++) {
			if (array[j] > max) {
				max = array[j];
			}
		}

		return max;
	}

	/**
	 * <p>Returns the maximum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static int max(final int[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns max
		int max = array[0];
		for (int j = 1; j < array.length; j++) {
			if (array[j] > max) {
				max = array[j];
			}
		}

		return max;
	}

	/**
	 * <p>Returns the maximum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static short max(final short[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns max
		short max = array[0];
		for (int i = 1; i < array.length; i++) {
			if (array[i] > max) {
				max = array[i];
			}
		}

		return max;
	}

	/**
	 * <p>Returns the maximum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 */
	public static byte max(final byte[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns max
		byte max = array[0];
		for (int i = 1; i < array.length; i++) {
			if (array[i] > max) {
				max = array[i];
			}
		}

		return max;
	}

	/**
	 * <p>Returns the maximum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 * @see IEEE754rUtils#max(double[]) IEEE754rUtils for a version of this method that handles NaN differently
	 */
	public static double max(final double[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns max
		double max = array[0];
		for (int j = 1; j < array.length; j++) {
			if (Double.isNaN(array[j])) {
				return Double.NaN;
			}
			if (array[j] > max) {
				max = array[j];
			}
		}

		return max;
	}

	/**
	 * <p>Returns the maximum value in an array.</p>
	 *
	 * @param array  an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws IllegalArgumentException if <code>array</code> is <code>null</code>
	 * @throws IllegalArgumentException if <code>array</code> is empty
	 * @see IEEE754rUtils#max(float[]) IEEE754rUtils for a version of this method that handles NaN differently
	 */
	public static float max(final float[] array) {
		// Validates input
		validateArray(array);

		// Finds and returns max
		float max = array[0];
		for (int j = 1; j < array.length; j++) {
			if (Float.isNaN(array[j])) {
				return Float.NaN;
			}
			if (array[j] > max) {
				max = array[j];
			}
		}

		return max;
	}

	/**
	 * Checks if the specified array is neither null nor empty.
	 *
	 * @param array  the array to check
	 * @throws IllegalArgumentException if {@code array} is either {@code null} or empty
	 */
	private static void validateArray(final Object array) {
		if (array == null) {
			throw new IllegalArgumentException("The Array must not be null");
		} else if (Array.getLength(array) == 0) {
			throw new IllegalArgumentException("Array cannot be empty.");
		}
	}

	// 3 param min
	//-----------------------------------------------------------------------
	/**
	 * <p>Gets the minimum of three <code>long</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the smallest of the values
	 */
	public static long min(long a, final long b, final long c) {
		if (b < a) {
			a = b;
		}
		if (c < a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the minimum of three <code>int</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the smallest of the values
	 */
	public static int min(int a, final int b, final int c) {
		if (b < a) {
			a = b;
		}
		if (c < a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the minimum of three <code>short</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the smallest of the values
	 */
	public static short min(short a, final short b, final short c) {
		if (b < a) {
			a = b;
		}
		if (c < a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the minimum of three <code>byte</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the smallest of the values
	 */
	public static byte min(byte a, final byte b, final byte c) {
		if (b < a) {
			a = b;
		}
		if (c < a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the minimum of three <code>double</code> values.</p>
	 *
	 * <p>If any value is <code>NaN</code>, <code>NaN</code> is
	 * returned. Infinity is handled.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the smallest of the values
	 * @see IEEE754rUtils#min(double, double, double) for a version of this method that handles NaN differently
	 */
	public static double min(final double a, final double b, final double c) {
		return Math.min(Math.min(a, b), c);
	}

	/**
	 * <p>Gets the minimum of three <code>float</code> values.</p>
	 *
	 * <p>If any value is <code>NaN</code>, <code>NaN</code> is
	 * returned. Infinity is handled.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the smallest of the values
	 * @see IEEE754rUtils#min(float, float, float) for a version of this method that handles NaN differently
	 */
	public static float min(final float a, final float b, final float c) {
		return Math.min(Math.min(a, b), c);
	}

	// 3 param max
	//-----------------------------------------------------------------------
	/**
	 * <p>Gets the maximum of three <code>long</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the largest of the values
	 */
	public static long max(long a, final long b, final long c) {
		if (b > a) {
			a = b;
		}
		if (c > a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the maximum of three <code>int</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the largest of the values
	 */
	public static int max(int a, final int b, final int c) {
		if (b > a) {
			a = b;
		}
		if (c > a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the maximum of three <code>short</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the largest of the values
	 */
	public static short max(short a, final short b, final short c) {
		if (b > a) {
			a = b;
		}
		if (c > a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the maximum of three <code>byte</code> values.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the largest of the values
	 */
	public static byte max(byte a, final byte b, final byte c) {
		if (b > a) {
			a = b;
		}
		if (c > a) {
			a = c;
		}
		return a;
	}

	/**
	 * <p>Gets the maximum of three <code>double</code> values.</p>
	 *
	 * <p>If any value is <code>NaN</code>, <code>NaN</code> is
	 * returned. Infinity is handled.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the largest of the values
	 * @see IEEE754rUtils#max(double, double, double) for a version of this method that handles NaN differently
	 */
	public static double max(final double a, final double b, final double c) {
		return Math.max(Math.max(a, b), c);
	}

	/**
	 * <p>Gets the maximum of three <code>float</code> values.</p>
	 *
	 * <p>If any value is <code>NaN</code>, <code>NaN</code> is
	 * returned. Infinity is handled.</p>
	 *
	 * @param a  value 1
	 * @param b  value 2
	 * @param c  value 3
	 * @return  the largest of the values
	 * @see IEEE754rUtils#max(float, float, float) for a version of this method that handles NaN differently
	 */
	public static float max(final float a, final float b, final float c) {
		return Math.max(Math.max(a, b), c);
	}

	//-----------------------------------------------------------------------
	/**
	 * <p>Checks whether the <code>String</code> contains only
	 * digit characters.</p>
	 *
	 * <p><code>Null</code> and empty String will return
	 * <code>false</code>.</p>
	 *
	 * @param str  the <code>String</code> to check
	 * @return <code>true</code> if str contains only Unicode numeric
	 */
	public static boolean isDigits(final String str) {
		if (StringUtils.isEmpty(str)) {
			return false;
		}
		for (int i = 0; i < str.length(); i++) {
			if (!Character.isDigit(str.charAt(i))) {
				return false;
			}
		}
		return true;
	}

	/**
	 * <p>Checks whether the String a valid Java number.</p>
	 *
	 * <p>Valid numbers include hexadecimal marked with the <code>0x</code>
	 * qualifier, scientific notation and numbers marked with a type
	 * qualifier (e.g. 123L).</p>
	 *
	 * <p><code>Null</code> and empty String will return
	 * <code>false</code>.</p>
	 *
	 * @param str  the <code>String</code> to check
	 * @return <code>true</code> if the string is a correctly formatted number
	 */
	public static boolean isNumber(final String str) {
		if (StringUtils.isEmpty(str)) {
			return false;
		}
		final char[] chars = str.toCharArray();
		int sz = chars.length;
		boolean hasExp = false;
		boolean hasDecPoint = false;
		boolean allowSigns = false;
		boolean foundDigit = false;
		// deal with any possible sign up front
		final int start = (chars[0] == '-') ? 1 : 0;
		if (sz > start + 1 && chars[start] == '0' && chars[start + 1] == 'x') {
			int i = start + 2;
			if (i == sz) {
				return false; // str == "0x"
			}
			// checking hex (it can't be anything else)
			for (; i < chars.length; i++) {
				if ((chars[i] < '0' || chars[i] > '9')
						&& (chars[i] < 'a' || chars[i] > 'f')
						&& (chars[i] < 'A' || chars[i] > 'F')) {
					return false;
				}
			}
			return true;
		}
		sz--; // don't want to loop to the last char, check it afterwords
		// for type qualifiers
		int i = start;
		// loop to the next to last char or to the last char if we need another digit to
		// make a valid number (e.g. chars[0..5] = "1234E")
		while (i < sz || (i < sz + 1 && allowSigns && !foundDigit)) {
			if (chars[i] >= '0' && chars[i] <= '9') {
				foundDigit = true;
				allowSigns = false;

			} else if (chars[i] == '.') {
				if (hasDecPoint || hasExp) {
					// two decimal points or dec in exponent
					return false;
				}
				hasDecPoint = true;
			} else if (chars[i] == 'e' || chars[i] == 'E') {
				// we've already taken care of hex.
				if (hasExp) {
					// two E's
					return false;
				}
				if (!foundDigit) {
					return false;
				}
				hasExp = true;
				allowSigns = true;
			} else if (chars[i] == '+' || chars[i] == '-') {
				if (!allowSigns) {
					return false;
				}
				allowSigns = false;
				foundDigit = false; // we need a digit after the E
			} else {
				return false;
			}
			i++;
		}
		if (i < chars.length) {
			if (chars[i] >= '0' && chars[i] <= '9') {
				// no type qualifier, OK
				return true;
			}
			if (chars[i] == 'e' || chars[i] == 'E') {
				// can't have an E at the last byte
				return false;
			}
			if (chars[i] == '.') {
				if (hasDecPoint || hasExp) {
					// two decimal points or dec in exponent
					return false;
				}
				// single trailing decimal point after non-exponent is ok
				return foundDigit;
			}
			if (!allowSigns
					&& (chars[i] == 'd'
					|| chars[i] == 'D'
					|| chars[i] == 'f'
					|| chars[i] == 'F')) {
				return foundDigit;
			}
			if (chars[i] == 'l'
					|| chars[i] == 'L') {
				// not allowing L with an exponent or decimal point
				return foundDigit && !hasExp && !hasDecPoint;
			}
			// last character is illegal
			return false;
		}
		// allowSigns is true iff the val ends in 'E'
		// found digit it to make sure weird stuff like '.' and '1E-' doesn't pass
		return !allowSigns && foundDigit;
	}
}
